1. Technical Field
The present invention relates to a positioning stage, a bump forming apparatus equipped with such a positioning stage, and a bump forming method performed using such a positioning stage.
2. Background Art
In manufacturing processes of electronic components, positioning stages for the positioning of wafers are generally used.
For example, referring to FIGS. 1(a) and 1(b), a wafer receiver 66 provided on an end of a supporting arm 65 supports a wafer 1. In a state where positioning rollers 67 are located outside the outer periphery of the wafer 1, a stopper arm 72 is moved with respect to the supporting arm 65. Using a bias force of a spring, the positioning rollers 67 and stopper rollers 74 sandwich the wafer 1 therebetween with an appropriate load (for example, see Patent Document 1).
In a case where a temperature change induces an electric charge, as in a piezoelectric substrate having pyroelectric properties, it is necessary to bring a charge-removing contact member into contact with a wafer placed on a positioning stage of a bump forming apparatus in order to remove the electric charge from the wafer. For example, referring to FIG. 2, a charge-removing member 1416 is provided with a cone-shaped hole 14166, and a ball 14115 provided at one end of a charge-removing contact member 14121 has a ground wire 14109 attached thereto. The other end of the charge-removing contact member 14121 is provided with a ball 14105 which is biased with a spring 14162. The charge-removing contact member 14121 is brought into contact with a surface of a wafer so as to ground the electrically charged surface (for example, see Patent Document 2).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 10-163214 (FIG. 11)
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2001-210664 (FIG. 20)
Moreover, when a wafer placed and positioned on a stage is heated in the course of a bump forming process, there are cases where the wafer gets damaged. This can occur when the heated wafer held in position undergoes thermal expansion, causing the internal stress generated within the wafer to exceed its strength.
In the case where a temperature change induces an electric charge on a wafer, if the positioning and charge-removing steps for the wafer are to be performed separately, the overall process and the equipment therefor will be complicated. This makes it difficult to achieve higher production efficiency.